gwen: Rebrand documentation to Gwen

Rewrite product prose and local path/command examples across the docs
to match the shipped application (gwen CLI, Gwen config paths, Gwen.app,
com.yrkaierx.Gwen). Upstream distribution channels, service URLs and
package identifiers stay factually intact.

docs/src/languages/purescript.md

@@ -1,6 +1,6 @@
 ---
 title: PureScript
-description: "Configure PureScript language support in Zed, including language servers, formatting, and debugging."
+description: "Configure PureScript language support in Gwen, including language servers, formatting, and debugging."
 ---
 
 # PureScript